Hey guys, I'm new to the board, but I'm having a little trouble with my engine. The other day my car started idling bad when a vacuum hose came off, put the hose on and it worked fine. Later that day another one sounded like it came off and the CEL came on. I looked high and low but could not find it to save my life. I checked all hoses zip-tied them on and im still hearing it faintly. The next day the CEL goes off and the car runs fine. Yesterday morning the CEL came on again and i could hear the sucking a little bit, but not as bad. Today is started acting up real bad. I noticed a black soot trail behind the exhaust on the ground. It was idling between 400-800 rpms with the whole car shaking. There is a very very very slow oil drip. You can hear the exhaust missing every second or so. The engine also vibrates after a second more than normal. Heres a list of the mods on my car to see if that helps. The only thing I've done in the last few days is install the new catalytic converter.

The car has 86,000 miles on it and the engine was rebuilt 2,100 miles ago.

greddy turbo upgrade
greddy FMIC
550cc injectors
greddy spark plugs
tru time cam gears
msd ignition
greddy bov
greddy oil cooler
ngk high performance plug wires
greddy evo catback
random tech 3" hi-flow cat
avc-r
s-afc
je pistons
eagle rods
arp head stud kit
arp bottom end stud kit
extreme motorsports 3" downpipe
optima battery
venom fuel pump

I'm running 6 psi of boost and the S-AFC is set to -19% to around -23% throughout the power band. I took it up to 5500 rpms for the first time today and the car started shuttering really bad right at 5500, the car felt like it was slowing down. This was in 3rd gear. In fourth it did the same thing at around 3500 rpms.

Any help would be gready appreciated, thanks guys.